On being an IPCC lead author: “It’s a lot of work because you have to do a lot of writing, and you have to be very careful because everything is reviewed, and re-reviewed, and re-reviewed again, and again, and again.”

On expectations for the sixth IPCC assessment report: “From the science perspective, I think there’ll be quite a bit of work on climate sensitivity, which remains a fairly controversial topic, certainly something which has still got quite a wide range of uncertainty on it.”

On her career highlights: “In the Grantham Institute it’s entirely strategic and motivated by trying to get society to be low carbon essentially.”

On her career regrets: “It’s a general perspective on my career is that I should have been more assertive.”

On unanswered climate science questions: “If we knew much more precisely how the climate responded to increased greenhouse gases we would be in a much stronger position to state that and push some action on it.”

On the impact of Trump on climate policy: “Within the US you’ve got the individual cities and states that are going for it more strongly than ever, almost because they’ve been revitalised, invigorated by Trump saying such stupid things.”

On what mitigation might look like by 2050: “There’ll be a lot more wind and solar, maybe there’ll be other exciting things, more local smart grids and things for sharing out electricity once the renewables have gained it.”

On what impacts might look like by 2050: “That’s the scary bit, isn’t it? That is the scary bit if you think of the coastal inundation to start with and the millions of people who live by the coast.”

On a net-zero goal for the UK: “I think in all these things you have to be pragmatic, you have to be ambitious, but you have to be pragmatic, there’s no point trying to force something to fit a curve that it’s not going to fit.”

On Brexit affecting research funding: “I do think that scientists by nature, and particularly in climate science, are very collaborative, and we just couldn’t do things really, or not as well, without talking to people across the world and working on projects together.”

Carbon Brief:Can I start by looking back on your academic career, which began with a degree in physics in Oxford, have I got that right?

Joanna Haigh: That’s right, yes.

CB: Was it always your intention to study weather and climate?

JH: No, it wasn’t. I mean, I always loved the weather and I’d always enjoyed being outside, and I’d done rather geeky things like built my own weather station. But to be honest, I didn’t really think of it as a career. When I was choosing A Levels I just chose what I was good at, which was physics and maths, and went off and did that. But it was a bit dry [laughs], so when I finished my first degree I wasn’t quite sure what I wanted to do, and I went off on a gap year around the Middle East looking at historical sites and things like that – and at the same time experiencing some fantastic and amazing weather, and I thought, “Aha. This is what I want to do.” So, I came back and went on the rather wonderful Masters course in meteorology at Imperial College, way back when. And that sort of set me off.

CB: At what point did you start to become aware of the issue of climate change?

JH: When you said you were coming I was trying to think about that, because of course we were aware of it back in the late 1970s. There was a lot of talk about the greenhouse effect, and there were the first big computer models that were being used to look at the effect of increased CO2. I think I was aware of it as a scientific issue, I don’t think I thought of it particularly as a life-threatening issue, or indeed I probably didn’t even relate it to environmental problems, which sounds silly now. But at that time that was the way that I was looking at it.

CB: How did you first get involved in climate change research? And what direction did your research take?

JH: My research was on stratospheric ozone, so this is back in the late 1970s – before the discovery of the ozone hole. But there were scientists that were saying that they thought that chlorofluorocarbons could have an impact on stratospheric ozone, and that would be bad for humans because it would increase UV [ultraviolet radiation], etc. In fact, that work had been going on for a while. What I was doing was looking at the combined effect of chlorofluorocarbons and increasing CO2 on stratospheric ozone. Now the chlorine compounds chemically deplete the ozone, the CO2 doesn’t have a chemical effect but it actually cools the stratosphere, so as a greenhouse gas it’s warming the lower atmosphere but it’s cooling the stratosphere. Sorry about this science lecture, is that alright?! [laughs]

As it cools the stratosphere, the reactions which destroy ozone slow down, and so actually increasing CO2 gives you an increase in ozone in the stratosphere. So my study was actually looking at these two things together and how they interact and what’s the net result. I came to the CO2 thing rather from an odd angle, I was looking at it from what it was doing in the stratosphere, higher up in the atmosphere. That was quite interesting work at the time, but then I came to think more about the other radiation effects in the atmosphere.

I was looking at solar radiation and infrared radiation, and the effects on the temperature and on the circulation of the atmosphere. I was starting in the stratosphere and I came down towards the surface. I was also doing things like using radiation to look at clouds and particles in the atmosphere and all this sort of business. I think I was morphing towards a climate interest for quite a long time.

CB: And then, am I right in thinking your research has focused on the influence of the sun on the climate?

JH: Yes.

CB: A popular [climate] sceptic argument is that the sun is ultimately responsible for our changing climate. How do we know that’s not the case?

JH: Right [laughs]. So what happened was I had been working on all these other things, and then there was a paper published in Science [in 1991] which showed this apparently extraordinary correlation between galactic cosmic rays and the temperature in the northern hemisphere. So that – let me get it the right way around – when there was more cosmic rays it was cooler. And the authors of that paper were saying that, “Look. All that recent global temperature change is due to the sun, because the sun influences the cosmic rays.” I thought, “That’s an interesting science question. I must have a look at that.” That’s how I got started, and again it was really from the aspect of solar radiation and its effects on the atmosphere, and whether or not that could be responsible for the global temperature change that was being reported.

Now, it subsequently transpired that that paper was very poor in the sense that it had extrapolated data and made assumptions that really weren’t valid, and in terms of showing a cause of global warming it was really not worth the paper it was written on, hardly. It was an interesting idea. But, in the meantime, I’d got interested in this whole issue about the sun’s effect on climate. I was really looking at it very much from a physics perspective, what the sun can and can’t do. I wasn’t setting out to prove that it was causing climate change, or indeed that it wasn’t. I was looking at the science, or trying to.

But, as you suggest, what happens is that people think that because you’re working on the sun’s effect on climate, you are therefore a climate change denier because you want it to be the sun that’s causing climate change and not greenhouse gases. So for a while I was on various sceptic’s circulations, and I was getting all the information from this rubbish climate stuff, which was really an insight into how that sector works, which is quite – a lot of is quite unpleasant. But, in the meantime, I think I did some quite interesting work on the sun and the climate, and I carried on doing that for quite a while.

My angle – which was different perhaps to what other people had done before – was looking at changes in solar ultraviolet radiation. When you think about climate change you generally think of the energy coming in and the energy going out, and that’s the total energy coming from the sun right the way across the whole of the spectrum. If you look at how much that varies – and we have measurements now – they show that it varies by quite a small amount, about a 10th of 1% over an 11-year cycle, or over longer multi-decadal timescales. So that’s really not going to be responsible for much more than a 10th or something of a degree of warming or cooling – indeed, in both directions.

But, actually, as the sun’s radiation varies by a 10th of a percent, it’s not the same across all of the spectrum. So that’s what it’s like in the middle of the visible spectrum – because that’s where most of the energy is – but actually in the ultraviolet it varies a lot more. So by the time you get out to a hundred nanometers, which is quite well into the ultraviolet, it’s doubling between solar max and solar min. If you’re looking at the sort of wavelengths that influence ozone – you see where I’m going now – it varies by a few percent over a solar cycle. So a few percent is not huge, but it’s a lot more than a 10th of a percent.

So I thought, “This is interesting. Let’s have a look at this,” and started looking at how changes in solar radiation – the ultraviolet radiation – affected stratospheric ozone, and then what that did to radiative forcing of climate change. And so, that’s what really got me involved in the whole climate thing. And then, I started looking at other things that were doing radiative forcing of climate and how they compare, and all the rest of it.

CB: You were a lead author on the third IPCC assessment report, which was published in 2001 – how did you find this experience?

JH: Well, I mean it was great fun because you’re spending a long time talking to a lot of people who are interested in the same sort of things that you are, in nice locations around the world. It’s a lot of work because you have to do a lot of writing, and you have to be very careful because everything is reviewed, and re-reviewed, and re-reviewed again, and again, and again. So it’s quite nice to be part of that community, and I enjoyed it very much. I was asked to do it the next time round and I refused because I thought it should be a turnover of people, because if you have climate change deniers who say that it’s all a sort of club of people who do this, then if you have a turnover of people it’s less likely to have that cast against you.

So I was a contributing author the next time around, but I wasn’t a lead author, I’ve contributed to the other subsequent reports. I think those IPCC reports are absolutely fantastic, and the amount of detail and the care and the work. Any information you want about climate change is in there, but they are getting so huge and so enormous now that nobody can be expected to read more than a small fraction of any of it. And you begin to wonder, perhaps they’ve outlived their usefulness as great big volumes, and it might be better to focus on particularly important angles that need working on, rather than just try and review everything in great detail every time. But people will disagree with me on that [laughs].

CB: Funnily enough, that is essentially what I was going to ask you next. The format that these reports take and the cycle of how long it takes to produce them – is this the best way for the IPCC to be effective, or are there other options?

JH: Yeah. The IPCC has already demonstrated that it can be more effective when it produced the 1.5C report last year. That was very much focused on a particular question: is getting to 1.5C different to getting to 2C? It was a much smaller report, and it was very focused on those questions. And even better, instead of dividing up into three sections – which is science and mitigation, adaptation and impacts – it put all three things into one volume – so that those aspects had to talk to each other, and that produced a much more punchy report than the usual ones.

CB: At the moment, there are various teams putting together the sixth assessment report, which will come out in a couple of years. What are your expectations for that report? What do you think might be the key advances since the fifth report?

JH: Well, there’ll be a lot more on mitigation efforts I suppose, to how we can keep global warming down, what can be done. From the science perspective, I think there’ll be quite a bit of work on climate sensitivity, which remains a fairly controversial topic, certainly something which has still got quite a wide range of uncertainty on it.

CB: You’ll shortly be retiring and stepping down from your position as co-director at the Grantham Institute. Can you pick out perhaps one highlight and one regret from your time at the Grantham Institute and Imperial College?

JH: Oh my goodness. Highlights. I mean, in my own career I suppose I’ve had two highlights really, big highlights. One was doing that solar stuff, and really getting some new results, and getting an FRS [being elected as a fellow of the Royal Society], which was pretty good I thought at the time! [laughs] And the second one is actually doing the Grantham Institute co-directorship because before that I was head of physics, which is a hugely big, demanding job with a massive department and very well worth doing. But really heavy going, and you go through the cycle of promotions and HR [human resources] issues and health and safety and teaching and all the rest of it, and you get through the year and you start the next year, and you sort of do this [sighs]. In the Grantham Institute it’s entirely strategic and motivated by trying to get society to be low carbon essentially. So it’s really inspirational, the staff here are just phenomenal. Really enjoyed that.

CB: Any regrets?

JH: Well, do you know, I think…my regrets…It’s more a question of not being assertive enough. In certain stages in your career, and you can see now that if you’d had a little bit more oomph, and you’d been a little bit more “actually, yes”, you could have done more. But you think, bit nervous or not quite sure or bit stand-offish and you don’t do it. So that’s not a very good answer, but I think it’s a general perspective on my career is that I should have been more assertive [laughs].

CB: Well, that leads me nicely onto the next question, which is: what advice would you give to young scientists embarking on a career in climate science?

JH: Yes. Well, what would my advice be? My advice would be don’t listen to advice! No. [Laughs] My advice would be to listen to what people are saying to you, and listen to what’s going on around, and try and learn from it. But don’t just do things because people tell you to do it, take a step back and say, “Is this right for me?” Because not everything is right for everybody, and somebody can give you advice that might be completely wrong for you although it might be right for somebody else. So you’re an individual, you’re different, you can…and you know for yourself in your guts what’s going to work for you. And try and be assertive [laughs] and stick to that.

CB: In a Nature article last year, you spoke about how to cope with online harassment from climate sceptics. How have you seen this issue emerge?

JH: For me personally, or in general?

CB: Both

JH: I’ve had it for many years. I think it got to a worst point after I did a Radio 4 programme called The Life Scientific. It has quite a wide audience and I got loads and loads of emails of which a few were nice, and many were really nasty and that set the scene. I stupidly said in that interview, “I always answer people when they email me.” So I thought I ought to live up to my claim – pompous twit that I am. I try and – unless it’s actually completely vile insults – I always reply once trying to explain why what they’re saying about the science of something is not quite correct and perhaps you should think about this. I generally don’t follow up an engagement – although I am at the moment, I’ve got somebody who’s going on and on and on, I’m very carefully explaining to them. It’s such a waste of time [laughs].

CB: Have you ever been tempted to venture onto social media?

JH: No, I’m so slow about doing things, I think if I went on social media I’d spend all day doing that and not focus on the day job. I know other people do it really well, I’m really happy that people in the Grantham Institute are doing the tweeting and whatever it is so that I don’t have to. I have written the occasional blog, does that count as social media?! [laughs]

CB: What advice might you have to scientists about how they deal with the unpleasant emails, as you described?

JH: Just remember these are very sad people that haven’t got anything better in their lives to do [laughs]. Because if you take it personally it can be really hurtful. But you have to think about why these people have these motives to state these things, which they clearly don’t understand, but they’re completely convinced – in all but very few cases where they do know what they’re talking about. You have to remember that they are not in possession of all the facts and you are – well, not all of them, but you might know better than they do – so you’ve got to try and be rational and explain things. Or, just when you think there’s no point, just don’t engage. But I think you do have to engage a bit, because you can’t just look like you’re snootily sitting separately in your ivory tower and you’re not talking to the person in the street.

CB: Changing subjects slightly, what climate science question do you wish had been answered during your career but wasn’t?

JH: Oh! [laughs] Well, I mean, if we knew much more precisely how the climate responded to increased greenhouse gases we would be in a much stronger position to state that – and push some action on it. I think we do know a lot – we do know that the temperature is rising, that it’s due to human activity, that it’s as a result of greenhouse gases. And we do know various patches over the globe are responding in certain ways, like the Mediterranean is drying and the monsoons are becoming more intense. But, if we could be much more precise about the sort of impacts that are going on, it would help the policy argument much better.

CB: Have you seen recent reports about some of the early results from CMIP6 model runs suggesting potentially higher equilibrium climate sensitivity (ECS)?

JH: Yes. I don’t know much about it, but I know that’s the case. We recently… I say we, NERC – the Natural Environment Research Council, which funds a lot of science research – was suggesting that there should be a strategic programme on the climate sensitivity and the role of clouds in the uncertainty and climate sensitivity. I was responsible for putting together a team and writing a proposal which went to NERC, and it was in competition with other areas of science to get funding to support that. And that was successful, so that’s something like £9-12m over five years for the community to work on climate sensitivity.

One of the things about climate sensitivity that is becoming clear – and I don’t do research on that myself but I understand the issues – has been something that’s been emerging in that – of course, you always need to use models to try and understand what’s going on, even if you’re basing it on data you need models to interpret the data – and it seems that the values of sensitivity that you get out are larger when you have a more highly resolved model, which is a quite interesting result in itself why that would be. But, it means if you’re doing the job better somehow or other you’re getting a higher number, so that would be one of the things that this programme is going to investigate.

CB: When does that programme run?

JH: It hasn’t started yet. It’s got the funds, but it hasn’t started yet.

CB: How optimistic are you for meeting the global warming limits set out in the Paris Agreement?

JH: Given that you said you’re writing all this down…! [laughs] I think it’s going to be very, very, very difficult to get to 1.5C. I think it would require immediate international action of the kind that is not happening now, and without that it’s just not going to happen and it’s going to be very difficult to get to 2C.

Having said that, the way that things happen, especially on the technology side, and technology is going much faster and get much cheaper than people are expecting, and get adopted much more readily. Look at wind power, for example, it’s now extraordinarily huge, and UK has got more renewables than fossil fuels on some days. We wouldn’t have known that was possible a few years ago. I think expect the unexpected really.

CB: When Donald Trump was elected as US president, you said you were “very scared” at the influence he might have on global climate policy. Two years later, what impact do you think he has had?

JH: I was very scared because I thought it would knock down the Paris Agreement like a house of cards. I really thought that if he was not… if US wasn’t going to do anything, why would any other countries? But the extraordinary thing is that it was only a couple of other countries that haven’t been enthusiastic, and even the big countries – China and India, Russia – they’re still doing it to a greater or lesser extent regardless of what the US is saying. And, within the US you’ve got the individual cities and states that are going for it more strongly than ever, almost because they’ve been vitalised, invigorated by Trump saying such stupid things.

It’s not been as bad as I’d feared. On the other hand, of course, he has been withdrawing funding for science and for environmental protection and all this sort of business, so it’s not all good.

CB: Looking ahead in terms of what’s before us for mitigation and adaptation, how do you think the world might look by the middle of the century – in terms of what efforts we’re doing and what impacts we’re seeing?

JH: Well, I think the efforts on air quality are already having an effect. In China, they know that they’ve got to do something about the air quality because it’s so bad, it’s affecting the health of everybody. And we’ve got the cutting down on emissions from cars – providing the motor manufacturers do what they say they’re meant to do. I think in terms of air quality that’s going to be much, much better.

In terms of renewables, there’ll be a lot more wind and solar, maybe there’ll be other exciting things – more local smart grids and things for sharing out electricity once the renewables have gained it. All these things, so lots and lots of very clever people thinking about all these ways of doing stuff, so I think it’ll be coming on fast.

JH: Very difficult. Very difficult. That’s the scary bit, isn’t it? That is the scary bit if you think of the coastal inundation, to start with, and the millions of people who live by the coast. And of people who are in areas where they’re on the margins of food security anyway, and now they’re not going to be able to grow enough food to live. And the impacts on political uncertainty when those people are migrating, you can get yourself very scared. I think without immediate action to stop these things, that’s the picture.

JH: [laughs] There’s a whole range of issues there! Clearly in the IPCC forecast – or predictions or prognoses, or whatever they call them – for the 1.5C report there’s a lot of BECCS – bioenergy and carbon sequestration – in those scenarios, and they don’t play out unless you’ve got that. There’s huge uncertainties about whether that is a) feasible and b) desirable for a number of other reasons, and Grantham Institute has just produced an excellent briefing paper on BECCS and things. It’s not a quick solution, even if the storage wasn’t a problem.

Likewise, industrial sequestration [of CO2] – you’ve got to be able to do it at scale, you’ve got to be able to get all the carbon out of these emissions and put it somewhere, and it’s got to stay there forever – forever and ever and ever – so it’s not just like doing it this week. I think there’s huge challenges there. Having said that, it does appear to be the case that we’re not going to be able to get to 2C, certainly not 1.5C without some use of sequestration. Whether you’d call that geoengineering, I don’t know, but I think that’s going to be needed.

Solar geoengineering, I’m afraid I think it’s a fool’s paradise, and I’ve been saying the same thing for many years. I know there’s arguments about, “Well, it’s just going to smooth us gently into a future without having the sharp increases [in temperature] now.” I think there’s a huge moral hazard there. People think of it as, “We can just do this and we don’t need to do any of the real issues with carbon reductions.” Apart from all the side effects and all the unintended consequences, and – number one – it’s not addressing the problem properly because what it’s doing is not stopping the trapping of heat radiation, it’s stopping the incoming solar radiation, and they happen at different places on the globe, so it’s not the same scenario. Maybe energy balance, but it’s not the same.

Who knows what’s going to happen to the clouds, and the hydrological cycle and all the other things. There’s people who’ve done models and they…actually, none of the models show the climate getting back to where it was – many of them show that actually you can control the surface temperature in this way. But, you’ve got people with some places in more rain and others with less rain and things, so to play around with the climate system like that – playing God – I think is just foolish.

CB: Having been involved in researching around solar influences throughout your career, have you seen the topic of solar geoengineering rise and fall over that time, because it seems to have a bit more traction more recently? Has that been the case previously as well?

JH: There’s always been the people who want to do weather modification, but I think that’s not the same as solar geoengineering. I think the rise of solar geoengineering has been quite slow, but has been going on for a good 10 years or so now. We’ve got people who are actually developing the little mirrors to go up into space to reflect the sunshine back to space. Big engineering projects working on this, and that’s been going on for, I don’t know, 15 years or something. It’s not that new, but certainly it’s got some proponents now who have ears in high places, and indeed big funding to investigate it further, so it’s not going to go away.

CB: Thinking of the UK more specifically, the Committee on Climate Change (CCC) will shortly be publishing new advice to the government on whether the UK should set a target for net-zero emissions. What do you think the date for a net-zero goal should be? And should there be different dates for CO2 and all greenhouse gases?

JH: Do you know, I thought that what the CCC had been asked to do was say how the UK could get to zero net emissions by 2050, but perhaps I’m wrong. Maybe I’m wrong. So that’s not answering your question [laughs]. I think in all these things you have to be pragmatic, you have to be ambitious, but you have to be pragmatic, there’s no point trying to force something to fit a curve that it’s not going to fit. So if it is that you can do some things before 2020 and other things you’d have to wait until 2060, well, then, yeah, just do it. I mean that’s obvious really [laughs].

CB: How do you see the UK’s role globally? Do you think it has the same level of influence since the Climate Change Act, is it still leading the world?

JH: Very interesting. I mean it was leading the world in the Climate Change Act and having the CCC and setting these legally binding targets, but it’s not doing anything about getting to the targets now, it’s stopped – all the green deal and the carbon sequestration, everything – it’s extraordinary. On the one hand they’re saying, “How are we going to get to net-zero by 2050?” On the other hand are saying, “Oh well, we’re not putting any funding into it.” So, it’s a mixed message, and we’re no longer on track to meet our five-year [carbon] budgets. We’ve been doing quite well up until now, but it’s moving away from it. We’re not going to look as a good international example on how to do it if we set up a load of policies and then don’t act on them.

The other thing, I’m afraid, is the whole Brexit stuff – the reputation of the UK in general, I mean…it would look pathetic. I mean look … we can’t organise ourselves, we can’t agree on anything, we can’t do anything. Why would anybody take our advice on anything at all [laughs], let alone really important stuff like climate?

CB: What impact do you see Brexit having on energy and climate policy?

JH: It’s difficult to assess isn’t it? It depends which way it goes because if we get the sort of deal where we manage to stay in with all the EU environmental legislation that’s good because that’s actually better than much of the stuff that we’ve had [historically] in the UK – apart from the five year carbon budgets. If we got a very extreme Brexit – and we’re chucking out all the environmental legislation and the extreme right-wing is just doing what it likes and raping and pillaging the environment – it’s very bad news.

CB: What impact do you see it having on the scientific research in the UK?

JH: Well, as I’m sure you know, we rely a lot on EU projects to fund scientists. That’s one thing is the funding, and the other thing is the actual scientists, so we get a lot of people coming here from mainland Europe, fantastic young people that do such a good job. While it would be good to grow more home people, I think we’d be definitely losing out in terms of the expertise in the universities.

CB: Have you seen any effect already?

JH: Yes. A number of academics – young academics from Europe – have gone home. Not because they’ve lost their jobs, or I don’t think they even particularly feel unwelcome at the university, I hope not. It’s just the whole aura, the whole country, and they’re thinking, “Well, might as well go home now rather than leave it a bit when I have to go.”

CB: How does it affect funding, because you’ve mentioned the programme you’ve got coming up that’s about to start, and those are four or five year-long projects. Is Brexit already affecting what happens after those or what happens to those ones?

JH: The one I was talking about was a UK budget one, so that’s not directly affected by the EU. The government has promised to continue up until the end of the contracts of any EU grant that’s already started before Brexit, so those ones are okay. But as I think you’re suggesting, what’s going to happen after that? We have no idea. When we had all the talk coming up to Brexit it was, “It will be great because we won’t be giving the Europeans all this money and we can spend it all on,” whichever is your favourite topic – 10 times the value of all the things that people wanted to do. So unless the government is going to produce a lot more money for direct science, it won’t happen. I do think that scientists by nature – and particularly in climate science – are very collaborative, and we just couldn’t do things really, or not as well, without talking to people across the world and working on projects together. So let’s hope that will continue even if the funding gets reorganised.

CB: The last topic I just wanted to ask you about was, as we speak there are protests on climate change going on in London by Extinction Rebellion, and there have been a series of school strikes across the world led by Greta Thunberg. What do you think of their tactics, the two different approaches, and would you be happy to join them?

JH: Absolutely. Yes. I think they’re doing a great job, and I know they’re disrupting people’s lives and it’s a bit irritating if you want to get somewhere and you can’t, but they’re making a point. And it’s on the front of the newspapers and it’s on the first item on the BBC. Good on you, kids. I didn’t go on the demonstration last week – I can’t remember what I was doing…I had a meeting at the Royal Society [laughs] – yes, I was worried about getting to my meeting at the Royal Society. No, I absolutely support them. Not in any violent and extreme way, but just shouting about it, absolutely. Causing people to sit up and take notice.

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